Semiconductor Device

ABSTRACT

A semiconductor device includes a header, a semiconductor chip fixed to the header constituting a MOSFET, and a sealing body of insulating resin which covers the semiconductor chip, the header and the like, and further includes a drain lead contiguously formed with the header and projects from one side surface of the sealing body, and a source lead and a gate lead which project in parallel from one side surface of the sealing body, and wires which are positioned in the inside of the sealing body and connect electrodes on an upper surface of the semiconductor chip and the source lead and the gate lead, with a gate electrode pad arranged at a position from the gate lead and the source lead farther than a source electrode pad.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a Continuation of U.S. application Ser. No.14/331,289, filed Jul. 15, 2014, which is a Continuation of U.S.application Ser. No. 13/628,899 filed Sep. 27, 2012, which is aContinuation of U.S. application Ser. No. 12/805,113 filed Jul. 13,2010, which is a Continuation of U.S. application Ser. No. 12/453,043filed Apr. 28, 2009, which is a Continuation of U.S. application Ser.No. 11/450,333 filed Jun. 12, 2006, which is a Divisional application ofU.S. application Ser. No. 10/823,734 filed Apr. 14, 2004, all content ofwhich is hereby incorporated by reference into this application.

BACKGROUND OF THE INVENTION

The present invention relates to a semiconductor device, and moreparticularly to a technique which is effectively applicable to asemiconductor device which seals a power source transistor chip such asa power MOSFET, an IGBT (Insulated Gate Bipolar Transistor), a bipolarpower transistor or the like. The above-mentioned semiconductor deviceis used in portable equipment, a laser beam printer, automobileinstalled electric equipment or the like.

As a power source transistor used in a charger of a mobile telephone, avideo camera or the like, a power source circuit of office automation(OA) equipment, automobile installed electric equipment, a low-voltagedrive power transistor has been known (see Japanese Patent ApplicationLaid-Open No. 2000-49184 (patent literature 1), for example).

Further, there has been also proposed a high power MOSFET whose JISpackage profile assumes a 10220 type or a 10247 type (see JapanesePatent Application Laid-Open No. 2000-77588 (patent literature 2), forexample).

SUMMARY OF THE INVENTION

The TO220 type semiconductor device (package) 90 has an profile shapeshown in FIG. 23 and FIG. 24. FIG. 23 is a plan view of package and FIG.24 is a side view of the package. An upper-surface side of a metal-madesupport board 91 which is referred to as a header is covered with asealing body 92 made of insulating resin. Three leads 93 to 95 projectfrom the sealing body 92 in parallel to each other. The leads 93 to 95are constituted of a gate (G) lead, a drain (D) lead and a source (S)lead. Further, the center lead 94 is offset in the inside of the sealingbody 92 and is integrally formed with the header 91. Although not shownin the drawing, a semiconductor chip in which a MOSFET is formed isfixed to an upper surface of the header 91. A back surface of thesemiconductor chip constitutes a drain electrode and is electricallyconnected with the header 91. Further, a gate electrode pad and a sourceelectrode pad are formed on an upper surface of the semiconductor chip.The gate electrode pad, the source electrode pad, and wire connectingportions (lead posts) of the gate lead 93 and the source lead 95 areconnected with each other using conductive wires.

FIG. 25 and FIG. 26 show a TO220 type semiconductor device whichinventors of the present inventions have studied before the inventorshave arrived at the present invention. FIG. 25 is a schematic plan viewof the semiconductor device in a state that a resin sealing body isremoved, and FIG. 26 is a cross-sectional view of the semiconductordevice corresponding to FIG. 25. In FIG. 25 and FIG. 26, to indicaterespective parts, with respect to the constitution which is common withthe constitution shown in FIG. 23 and FIG. 24, the same referencenumerals are used as it is.

A header 91 includes a mounting hole 96 for fixing a package 90 to amounting board. A semiconductor chip 97 is fixed to a region inside aV-shaped groove frame 98 formed in a rectangular ring shape by means ofan adhesive material.

A gate electrode pad 99 and a source electrode pad 100 are mounted on anupper surface (first main surface) of the semiconductor chip 97. Thegate electrode pad 99 and a wire connecting portion (lead post) 93 a ofa gate lead 93 are connected with each other by a conductive wire 101,while a source electrode pad 100 and a wire connecting portion 95 a of asource lead 95 are connected with each other by a conductive wire 102.To reduce the ON resistance, two wires 102 are used for connecting thesource electrode pad 100 and the source lead 95. These wires 102 arerespectively formed of a bold line (aluminum line having a diameter of30 to 500 μm, for example) compared to the wires 101 (aluminum linehaving a diameter of 125 μm, for example) which connect the gateelectrode pad 99 and the gate lead 93.

Although an insulating protective film is formed on the upper surface ofthe semiconductor chip 97, respective electrodes are exposed at bottomsof opening portions which are formed by partially removing theprotective film and these exposed portions constitute the gate electrodepad 99 and the source electrode pad 100. The source electrode pad 100 isformed with a large width to allow the connection of two wires. That is,the source electrode pad 100 is formed in an elongated manner in thedirection orthogonal to the extending direction of the leads. The sourceelectrode pad 100 is formed substantially at the center of thesemiconductor chip 97. Since the fine wire is connected to the gateelectrode pad 99, the gate electrode pad 99 is sufficiently smallcompared to the source electrode pad 100. Further, as also described inthe patent literature 2, the gate electrode pad 99 is provided at acorner of the semiconductor chip 97 and at a position close to the leadpost 93 a which constitutes a distal end of the gate lead 93. That is,the gate electrode pad 99 is arranged close to the lead posts 93 a, 95 aof the leads 93, 95 than the source electrode pad 100. In other words,the gate electrode pad 99 is positioned between the gate lead post 93 aand the source electrode pad 100.

However, when the gate electrode pad 99 is configured to be arranged atthe corner side of the semiconductor chip 97 close to the lead posts,along with the increase of a chip size of the semiconductor chip, thegate electrode pad 99 and the lead post 93 a become further closer toeach other. Accordingly, at the time of performing the wire bonding inthe package manufacturing step, a bonding tool is brought into contactwith a stepped portion of the lead and hence, bonding becomes difficult.That is, the wire bonding is ultrasonic wave bonding which uses a wedgebonding tool and hence, at the time of connecting one end of the wire tothe gate electrode pad 99 as the first bonding, the bonding tool(capillary) which holds the wire is brought into contact with the gatelead post 93 a. Accordingly, the ultrasonic vibration cannot beeffectively applied to the wire bonding portion and hence, it isdifficult to perform the highly reliable wire bonding.

Further, the source lead 95 is arranged at the outside of the packageand the source electrode pad 100 is arranged at the center side of thepackage and hence, the source wire 102 extends in the direction whichintersects the direction that the lead extends.

Accordingly, compared to a case in which the source wire 102 is formedto extend in the direction that the lead extends, it is necessary toincrease a pitch between the source wires 102 and hence, it is difficultto form a large number of source wires 102.

Still further, as the wire 102 which is connected to the sourceelectrode pad 100, a wire having a large diameter of 30 to 500 μm isused as described above and hence, the number of wires which areconnected with the source electrode pad and the lead post 95 a islimited whereby lowering of the ON resistance of the package is alsolimited.

It is an object of the present invention to provide a semiconductordevice having low ON resistance.

It is another object of the present invention to provide a semiconductordevice which can fix a semiconductor chip having a larger size onto asupport board.

It is still another object of the present invention to provide amanufacturing method of a semiconductor device which exhibits the highelectric reliability.

The above-mentioned object, other objects and novel features of thepresent invention will become apparent from the description of thisspecification and attached drawings.

To briefly explain the summary of typical inventions among theinventions disclosed in this specification, they are as follows.

(1) The semiconductor device of the present invention includes ametal-made support board which has at least a portion thereof coveredwith a sealing body made of insulating resin and has a lower surfacethereof exposed from the sealing body thus constituting a firstelectrode, a first electrode lead which is contiguously formed with thesupport board and projects from one side surface of the sealing body, asecond electrode lead and a control electrode lead which project fromthe above-mentioned one side surface of the sealing body and extendparallel to the first electrode lead, a semiconductor chip which iscovered with the sealing body, has a first electrode on a lower surfacethereof, has a second electrode pad and a control electrode pad on anupper surface thereof, and has a lower surface thereof fixed to thesupport board by a conductive bonding material, connecting means whichis positioned in the inside of the sealing body and electricallyconnects the second electrode pad and the second electrode lead, andconnecting means which is positioned in the inside of the sealing bodyand electrically connects the control electrode pad and the controlelectrode lead, wherein the second electrode pad is arranged at aposition close to the control electrode lead and the second electrodelead and the control electrode pad is arranged at a position far fromthe control electrode lead and the second electrode lead.

A field effect transistor is incorporated into the semiconductor chip,wherein the first electrode lead constitutes a drain lead thereof, thecontrol electrode lead constitutes a gate lead thereof and the secondelectrode lead constitutes a source lead. One side of the semiconductorchip which has a quadrangular shape faces the lead posts of the gatelead and the source lead in an opposed manner, and a gate electrode padis positioned at one corner portion of a semiconductor chip contiguouslywith a side opposite to the opposingly facing surface.

The gate electrode pad and the gate lead are connected with each otherusing one wire, the source electrode pad and the source lead areconnected using a plurality of wires, and the plurality of wires have alarger diameter and a shorter length than the wire which connects thegate electrode pad and the gate lead.

(2) In the above-mentioned constitution (1), the source electrode padand the source lead have large widths, and the source electrode pad andthe source lead are formed of a conductive plate having a wide widthwhich is formed of a resilient metal plate molded in a ribbon strap orin a given shape.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic plan view of a semiconductor device according toone embodiment (embodiment 1) of the present invention in a state that aresin sealing body is removed;

FIG. 2 is a cross-sectional view of the semiconductor device of theembodiment 1;

FIG. 3 is a schematic plan view of a semiconductor chip which isincorporated in the semiconductor device of the first embodiment;

FIG. 4 is a cross-sectional view taken along a line A-A in FIG. 3;

FIG. 5 is a plan view showing a portion of the chip in a state that agate pad is arranged at a corner of the chip;

FIG. 6 is plan view of the portion of the chip in a state that a gatepad is arranged in the midst of a side of the chip;

FIG. 7 is a plan view showing a lead frame to which a chip is fixed inthe manufacture of the semiconductor device of the embodiment 1;

FIG. 8 is a plan view showing a lead frame to which wires are connectedin the manufacture of the semiconductor device of the embodiment 1;

FIG. 9 is a schematic plan view of a semiconductor device according toanother embodiment (embodiment 2) of the present invention in a statethat a resin sealing body is removed;

FIG. 10 is a cross-sectional view of the semiconductor device of theembodiment 2;

FIG. 11 is a schematic plan view of a semiconductor device according toanother embodiment (embodiment 3) of the present invention in a statethat a resin sealing body is removed;

FIG. 12 is a cross-sectional view of the semiconductor device of theembodiment 3;

FIG. 13 is a schematic plan view of a semiconductor device according toanother embodiment (embodiment 4) of the present invention in a statethat a resin sealing body is removed;

FIG. 14 is a schematic plan view of a semiconductor device according toanother embodiment (embodiment 5) of the present invention in a statethat a resin sealing body is removed;

FIG. 15 is a cross-sectional view of the semiconductor device of theembodiment 5;

FIG. 16 is a plan view of a lead frame which is used in the manufactureof the semiconductor device of the embodiment 5;

FIG. 17 is a schematic plan view of a semiconductor device according toanother embodiment (embodiment 6) of the present invention in a statethat a resin sealing body is removed;

FIG. 18 is a cross-sectional view of the semiconductor device of theembodiment 6;

FIG. 19 is a schematic plan view of a semiconductor device according toanother embodiment (embodiment 7) of the present invention in a statethat a resin sealing body is removed;

FIG. 20 is a cross-sectional view of the semiconductor device of theembodiment 7;

FIG. 21 is a schematic plan view of a semiconductor device according toanother embodiment (embodiment 8) of the present invention in a statethat a resin sealing body is removed;

FIG. 22 is a schematic cross-sectional view of a semiconductor deviceaccording to another embodiment (embodiment 9) of the present invention;

FIG. 23 is a schematic plan view of a conventional semiconductor device;

FIG. 24 is a side view of the semiconductor device shown in FIG. 23;

FIG. 25 is a schematic plan view of a semiconductor device in a statethat a resin sealing body is removed before inventors have arrived atthe present invention; and

FIG. 26 is a cross-sectional view of the semiconductor device shown inFIG. 25.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, embodiments of the present invention are explained indetail in conjunction with drawings. Here, in the whole drawings forexplaining the embodiments of the invention, parts having identicalfunctions are given same symbols and the repeated explanations thereofare omitted.

Embodiment 1

FIG. 1 to FIG. 8 are views relating to a semiconductor device as oneembodiment of the present invention (embodiment 1). FIG. 1 is aschematic plan view of the semiconductor device in a state that a resinsealing body is removed, FIG. 2 is a cross-sectional view of thesemiconductor device, FIG. 3 is a schematic plan view of a semiconductorchip which is incorporated into the semiconductor device, FIG. 4 is across-sectional view taken along a line A-A in FIG. 3, FIG. 5 is a planview showing a portion of a chip which shows a state in which a gateelectrode pad is arranged at a corner of the chip and FIG. 6 is a planview showing a portion of a chip which shows a state in which a gateelectrode pad is arranged in the midst of a side of the chip.

In the embodiment 1, an example in which the present invention isapplied to a vertical type power transistor (semiconductor device) 1 isexplained. That is, a semiconductor chip which incorporates a fieldeffect transistor is incorporated into the semiconductor device 1,wherein the field effect transistor includes a drain (D) electrode as afirst electrode, a source (S) electrode as a second electrode and a gate(G) electrode as a control electrode.

The power transistor 1 comprises, as shown in FIG. 1 and FIG. 2, asealing body 2 which is formed of insulating resin, a metal-made supportboard (header) 3 which has at least a portion thereof covered with thesealing body 2, has the lower surface thereof exposed from the sealingbody 2 and constitutes the first electrode, a first electrode lead(drain lead) 4 which is formed contiguously with the support board 3,projects from one end surface of the sealing body 2 and is bent inone-stage step-like manner in the midst thereof, a second electrode lead(source lead) 5 and a control electrode lead (gate lead) 6 which projectfrom the above-mentioned one end surface of the sealing body 2 in astate that these leads 5, 6 are arranged in parallel with the firstelectrode lead 4. The source lead 5 and the gate lead 6 have the sameheight as the drain lead 4. The support board 3 has a large thicknessand the leads have a small thickness and these parts are formed of adeformed member having different thicknesses partially.

Further, a semiconductor chip 7 is arranged in the inside of the sealingbody (package) 2. As shown in FIG. 4, the semiconductor chip 7 has thestructure in which a vertical type power MOSFET is formed therein and afirst electrode (drain electrode) 10 is formed on a lower surfacethereof. As shown in FIG. 3 and FIG. 1, the semiconductor chip 7includes a second electrode (source electrode) pad 11 and a controlelectrode (gate electrode) pad 12 on a main surface (upper surface)thereof. The drain electrode is made of Ti, Ni or Au. Further, thesource electrode pad 11 and the gate electrode pad 12 are made of Al.

As shown in FIG. 2, a drain electrode not shown in the drawing which isformed on the lower surface the semiconductor chip 7 is fixed to thesupport board (header) 3 by way of a conductive adhesive material (notshown in the drawing). Further, the source lead 5 and the gate lead 6have lead posts 5 a, 6 a at distal ends thereof which extend in theinside of the sealing body 2, wherein these lead posts 5 a, 6 a havelarge widths. These lead posts 5 a, 6 a are respectively connected withthe source electrode pads 11 and the gate electrode pad 12 of thesemiconductor chip 7 via wires 14, 15.

The wire 15 which connects the lead post 6 a of the gate lead 6 with thegate electrode pad 12 is a fine Al line having a diameter of, forexample, 125 μm. The lead post 5 a of the source lead 5 and the sourceelectrode pad 11 are connected with each other by a plurality of wires14. Although two wires 14 are shown in the drawing, the number of thewires 14 may be increased to lower the ON resistance. The wires 14 havea diameter of about 300 to 500 μm. For example, the diameter of thewires 14 may be 500 μm which is greater than a diameter of the wire 15.The wire 15 is also formed of an Al line. Further, to lower the ONresistance, a connecting length of the wire 14 is set to 5 mm or less.Further, either wire is bonded by rubbing using ultrasonic waves.Accordingly, when wire bonding is applied to the electrode pad on themain surface of the semiconductor chip 7, it is necessary to perform thewire bonding in such a manner that a bonding tool which holds the wireis not brought into contact with a lead post which is arranged at aposition one stage higher than the bonding tool.

In this embodiment 1, as shown in FIG. 1, the gate electrode pad 12 isarranged at a position far from the lead post, the source electrode pad11 is large, and the wires 14 are bonded to the source electrode pad 11at respective positions along the center line of the source electrodepad 11 and hence, there is no possibility that a bonding tool is broughtinto contact with the lead post whereby the reliable wire bonding can berealized.

Here, the semiconductor chip 7 is explained briefly. As shown in FIG. 3,the semiconductor chip 7 has a quadrangular shape as a plan view. Thesource electrode pad 11 has a large width (rectangular shape) and, atthe same time, is mounted on the chip at a position offset to one sideof the chip. A side of the semiconductor chip 7 which is arranged closeto the source electrode pad 11 (a side which forms a lower edge in FIG.3) constitutes a side which opposingly faces the lead posts when thesemiconductor chip 7 is fixed to the support board 3. At one cornerportion (the left-side corner in FIG. 3) of the chip which is formedcontiguously with a side (a side which forms an upper edge in FIG. 3) ofthe semiconductor chip 7 opposite to the opposingly facing side, thegate electrode pad 12 is positioned. As shown in FIG. 1, the gateelectrode pad 12 is offset from the center line of the source electrodepad 11 by a distance e.

The semiconductor chip 7 is, although a size thereof is not specificallylimited, a length of one side is set to 8 to 9 mm. Further, since thewire 15 has a diameter of 125 μm, the gate electrode pad 12 has a squareshape having one side of approximately 0.3 to 0.5 mm. On the other hand,for example, since a plurality of wires 14 are connected to the sourceelectrode pad 11 along the center line of the source electrode pad 11,the size of the source electrode pad 11 is set such that a longitudinalsize is 4 mm and a lateral size (width) is 7 mm, for example.

FIG. 4 is an enlarged cross-sectional view of a portion taken along aline A-A in FIG. 3. The semiconductor chip 7 is formed based on ann⁺type silicon semiconductor board 20 having n⁻type epitaxial layer 21on a main surface thereof. The power transistor 1 is formed of avertical MOSFET and a large number of cells (transistors) are arrangedin rows in a plan view. In this embodiment, the respective transistorcells have the trench constitution. A p⁻type channel (ch) layer 22 isformed on a given region of the epitaxial layer 21 and, at the sametime, a p⁻type well layer 23 which constitutes a guard ring is formedaround an outer periphery of the p⁻type channel (ch) layer 22.

Further, a large number of trenches (grooves) 25 are formed in the cellforming region such that the trenches penetrate the channel (ch) layer22. The trench 25 is also formed in the well layer 23. A region definedbetween the trench which is formed in the well layer 23 and the trenchwhich constitutes the cell positioned at the outermost periphery in theinside of the trench formed in the well layer 23 constitutes an invalidregion f which is not used as a cell. The invalid region f is a regionwhich is sandwiched by two lines formed of a chain double-dashed line inFIG. 3. The region surrounded by the invalid region f constitutes avalid region h in which the cells are formed. The larger a width of thevalid region h, the number of cells can be increased and an output ofthe power transistor 1 can be increased.

In this embodiment 1, the gate electrode pad 12 is provided at onecorner of the semiconductor chip 7 and is positioned outside the region(valid region h) which is surrounded by the invalid region f. As shownin FIG. 6, it is possible to position the gate electrode pad 12 in themidst portion of a side of the chip which is contiguous with a sidewhich opposingly faces the lead posts and also orthogonal to theopposingly facing side. To make the gate electrode pad 12 correspond tothe lead post 6 a of the gate lead 6, the gate electrode pad 12 isarranged in the midst of the left side of the chip.

When the gate electrode pad 12 is provided at the midst portion of oneside of the chip, as shown in FIG. 6, the invalid region f appears alongthree sides of the gate electrode pad 12. On the other hand, when thegate electrode pad 12 is provided at the corner of the chip, as shown inFIG. 5, the invalid region f appears only along two sides of the gateelectrode pad 12. Accordingly, by providing the gate electrode pad 12 atthe corner, it is possible to reduce an area of the invalid region f.Since an area of the valid region h can be increased corresponding to areduced amount of the invalid area f, it is possible to increase thenumber of cells. In this embodiment, for example, the cell has a squareshape having each side of 3 to 5 μm. Since one side of the gateelectrode pad 12 is 300 to 500 μm, by forming the gate electrode pad 12at the corner, it is possible to form a larger number of cells.

A polysilicon gate layer 26 which constitutes a gate electrode is formedin the inside of the trench 25 and a gate insulation film 27 is formedbelow the polysilicon gate layer 26. Further, a p⁺ region 28 is formedon a center surface layer portion of the channel layer 22 which issurrounded by the trench. With respect to the channel layer 22 in thecell portion, an n⁺type source region 29 is formed in a region rangingfrom the outside of the p⁺ region 28 to the trench. The trench portion,that is, the gate insulation film 27 and the polysilicon gate layer 26are covered with an insulation film 32 and the source electrode 33 isformed over the insulation film 32. The source electrode 33 iselectrically connected with the p⁺ region 28 and the source region 29 atopening portions where the insulation film 32 is not formed.

At the trench 25 portion which is positioned outside the invalid regionf, a thick insulation film (LOCUS) 34 is formed contiguously with thegate insulation film 27. The thick insulation film (LOCUS) 34 extendsbeyond the outer periphery of the well layer 23. The polysilicon gatelayer 26 which is embedded in the trench 25 positioned outside theinvalid region f extends over the midst portion above the thickinsulation film 34 and forms a peripheral gate line 35. Further, theperipheral gate line 35 and the thick insulation film 34 are alsocovered with the insulation film 32. Over the insulation film 32portion, a gate electrode line 36 is formed. The gate electrode line 36is electrically connected with the polysilicon gate layer 26 through anopening partially formed in the insulation film 32.

As shown in FIG. 4, the insulation film 32 assumes a state in which theinsulation film 32 does not reach the periphery of the semiconductorchip 7. Further, a surface of the epitaxial layer 21 which is arrangedaway from the insulation film 32 is slightly etched and hence is loweredby one stage. Over this lowered portion, the periphery of the insulationfilm 32 is covered with the guard ring 37 which assumes the samepotential as the drain electrode. Over a surface layer of the epitaxiallayer 21 below the guard ring 37, a p⁺type guard ring contact layer(HCNT) 38 is formed. The guard ring contact layer (HCNT) 38 extends toan edge of the semiconductor chip 7. Further, over a surface layerportion of the epitaxial layer 21 inside the guard ring 37, a n⁺typechannel stopper layer (S) 39 is formed. Since the guard ring contactlayer (HCNT) 38 assumes the potential of the guard ring 37, the channelstopper layer (S) 39 has an advantageous effect that the layer 39 guardsthe progress of a deplete layer.

The main surface of the semiconductor chip 7 is, as shown in FIG. 4,covered with and protected by an insulation film 40. Further, openingsare selectively formed in the insulation film 40. The opening portionsconstitute the source electrode pad 11 and the gate electrode pad 12shown in FIG. 3 and FIG. 1.

On the other hand, in the center portion of the sealing body 2 which isarranged away from the semiconductor chip 7, a mounting hole 8 which isused at the time of mounting the power transistor 1 on the mountingboard or the like is formed. In the support board 3 which supports thesealing body 2 in which the mounting hole 8 is formed, a hole 9 which isconcentric with the mounting hole 8 and is larger than the mounting hole8 is formed. Further, on the main surface of the support board 3, aV-shaped groove is formed in a quadrangular frame form. The resin whichforms the sealing body 2 is also filled in the inside of the V groove ofthe V groove frame 41. Due to the provision of the V groove frame 41, itis possible to make the intrusion of moisture into an interface betweenthe support board 3 and the sealing body 2 difficult. Further,press-deformable portions 42 are provide over two positions at bothsides of the support board 3 and the resin which forms the sealing body2 is positioned above and below the press-deformable portions 42 thusmaking peeling-off of the sealed body 2 from the support board 3difficult. Due to such a constitution, the moisture resistance of thepower transistor 1 is enhanced.

Next, the manufacturing method of the semiconductor device (powertransistor 1) of this embodiment 1 is explained in conjunction with FIG.7 and FIG. 8. FIG. 7 is a plan view showing a lead frame to which a chipis fixed in the manufacture of the power transistor of the embodiment 1and FIG. 8 is a plan view showing a lead frame to which wires areconnected.

In the manufacture of the power transistor 1, the lead frame 45 isprepared as shown in FIG. 7. To manufacture a plurality of powertransistors 1, the lead frame 45 is configured such that a plurality ofunit frames 46 each of which is served for manufacturing one powertransistor 1 are connected in a strip form in parallel.

The unit lead frame 46 has a pattern in which three leads 6, 4, 5explained in conjunction with FIG. 1 extend a given length. The unitlead frame 46 also includes a narrow dam 47 which extends in thedirection orthogonal to these three leads 6, 4, 5 to hold these leadsand a frame piece 48 which connects distal end portions of three leads6, 4, 5. The dam 47 is provided at a position close to the sealing body2.

The unit lead frames 46 are connected with each other by these dams 47and the frame piece 48. Further, the manufacturing method also adoptsthe structure in which a distal-end-side portion of the support board(header) 3 is also connected with the neighboring header by theconnecting portion 50. FIG. 7 shows a state in which three unit leadframes 46 are arranged in parallel to each other. Further, the supportboard 3 is lowered by one stage than the respective leads (see FIG. 2).Guide holes 49 are formed in the frame piece 48. The guide holes 49 areused for transporting the lead frame 45 and for positioning the leadframe 45. The lead frame 45 is formed into a pattern by blanking astrip-like metal plate (profile) made of copper alloy or the like whichincreases a thickness thereof with a given width at one side thereofusing a precision press and, at the same time, by raising a thin portionone stage higher than a thick portion by bending the thin portion (thestep difference being 1.8 mm). The thick portion constitutes theabove-mentioned support board 3 and has a thickness of 1.26 mm and thethin portion constitutes the above-mentioned gate leads 6, the drainlead 4 and the source leads 5 and has a thickness of 0.6 mm. Distal endsof the source leads 5 and the gate leads 6 form the lead posts 5 a, 6 ahaving large widths.

The semiconductor chips 7 are fixed to respective support boards 3 ofthe lead frame 45 having such a constitution at given positions by wayof an adhesive material. Here, the semiconductor chip 7 is fixed in astate that the source electrode pad 11 is positioned at the positionclose to the lead posts 5 a, 6 a and the gate electrode pad 12 ispositioned at the position far from the lead posts 5 a, 6 a (see FIG.7).

Next, as shown in FIG. 8, the source electrode pad 11 and the lead posts5 a of the source lead 5 are electrically connected with each otherusing the Al wires having a diameter of 500 μm. The source electrode pad11 and the source lead 5 are connected with each other using two wires14. The wires 14 are connected by ultrasonic wave wire bonding.

Next, the gate electrode pad 12 and the lead post 6 a of the gate lead 6are connected with each other using the Al wire 15 having a diameter of125 μm. The wire 15 is connected by ultrasonic wave wire bonding. Evenwhen the distal end of the wire 15 is connected to the gate electrodepad 12 by ultrasonic wave wire bonding, since the gate electrode pad 12is arranged at the position far from the lead post 6 a, there is nopossibility that the bonding tool is brought into contact with the leadpost 6 a and hence, the reliable wire bonding can be performed.Accordingly, it is possible to fix the semiconductor chip 7 to thesupport board 3 such that semiconductor chip 7 is arranged close to thelead posts 5 a, 6 a. Due to such provision, it is possible to shortenthe length of the support board 3 and to increase the size of thesemiconductor chip 7 to be fixed and hence, the miniaturization of thepower transistor 1 and the increase of the output due to thelarge-sizing of the chip can be realized.

Next, as indicated by a dotted line in FIG. 8, the sealing body 2 isformed by a transfer molding method or the like using insulating resin.Subsequently, the dam 47 between respective leads and the connectingportion 50 are removed by cutting and, thereafter, respective leads arecut whereby a plurality of power transistors 1 shown in FIG. 1 and FIG.2 are manufactured.

Next, when necessary, solder plating treatment is applied to surfaces ofthe leads projecting from the sealing body 2 so as to form mountingsolder plating films not shown in the drawing on given positions of theleads and the support board 3.

The power transistor 1 of this embodiment 1 can be, for example, used asa switch of a control system of an automobile, for example. For example,the power transistor has the output of 10 to 15 W (power source voltage:10 to 20V).

According to this embodiment 1, following advantageous effects can beobtained.

(1) Since the gate electrode pad 12 is arranged at the position far fromthe lead post 6 a of the gate lead 6, at the time of performing the wirebonding, there is no possibility that the bonding tool which holds thewire is brought into contact with the lead post 6 a of the gate lead 6.As a result, it is possible to arrange the semiconductor chip 7 to befixed to the support board (header) 3 at the position close to the leadpost 6 a side of the gate lead 6 and hence, the support board 3 can bemade small correspondingly whereby the miniaturization of the powertransistor (semiconductor device) can be realized.

(2) Due to the above-mentioned advantageous effect, it is possible toarrange the semiconductor chip 7 to be fixed to the support board 3close to the lead post 6 a side of the gate lead 6 and hence, it ispossible to fix the semiconductor chip 7 having the larger size to thesupport board 3. As a result, it is possible to increase the output ofthe power transistor 1.

(3) Since the source electrode pad 11 can be arranged close to thesource lead 5, a length of the wire 14 which connects the sourceelectrode pad 11 and the source lead 5 can be shortened whereby the ONresistance can be reduced.

Embodiment 2

FIG. 9 is a schematic plan view of a semiconductor device according toanother embodiment (embodiment 2) of the present invention in a statethat a resin sealing body is removed, and FIG. 10 is a cross-sectionalview of the semiconductor device.

This embodiment 2 is characterized in that, in a power transistor 1 ofthe embodiment 1, a source electrode pad 11 and a source lead 5 areconnected with each other using a conductive plate 52. In thisembodiment, as the conductive plate 52, a ribbon strap 53 formed of aresilient Al foil having a thickness of approximately 150 to 250 μm isused.

In this embodiment, for facilitating the connection using the conductiveplate 52, as shown in FIG. 9, the source lead 5 is arranged at thecenter, the gate lead 6 is arranged at the left side of the source lead5 and the drain lead 4 is arranged at the right side of the source lead5. The lead post 5 a of the source lead 5 has a width larger than widthsof other leads so as to enable the connection of the conductive plate52. For example, the lead post 5 a has the substantially same width asthe source electrode pad 11. Accordingly, a ribbon strap having a largewidth can be connected to the lead post 5 a. The ribbon strap 53 isformed of a resilient Al foil and is connected with the source electrodepad 11 and the lead post 5 a of the source lead 5 by ultrasonic wavebonding.

That is, in the manufacture of the power transistor 1, first of all, alead frame 45 shown in FIG. 7 is prepared. The lead frame 45 is formedof a sheet of metal plate which is patterned and is bent by one stage atone portion thereof. The lead frame 45 includes a support board whichconstitutes a first electrode (drain electrode) and to which asemiconductor chip is fixed, a first electrode lead (drain lead 4) whichsupports the support board at a distal end thereof, and a secondelectrode lead (source lead 5) and a control electrode lead (gate lead6) which extend in parallel with the first electrode lead.

Further, a quadrangular semiconductor chip 7 having the first electrode(drain electrode) on a lower surface thereof and a second electrode pad(source electrode pad 11) and a control electrode pad (gate electrodepad 12) on an upper surface thereof is prepared.

Next, the semiconductor chip 7 is fixed to the support board 3 by way ofa conductive bonding material at the first electrode portion (drainelectrode) thereof.

Next, the source electrode pad 11 of the semiconductor chip 7 and thesource electrode pad 11 are electrically connected with each other usingconnecting means and, at the same time, the gate electrode pad 12 of thesemiconductor chip 7 and the gate lead 6 are electrically connected witheach other using connecting means. Although the gate electrode pad 12and the gate lead 6 are connected with each other by an Al wire 15having a diameter of 125 μm, the source electrode pad 11 and the sourceelectrode pad 11 are connected with each other by the above-mentionedribbon strap 53. In this case, as shown in FIG. 9, the wire 15 traversesa corner portion of the ribbon strap 53 and hence, it is necessary toconnect the gate electrode pad 12 and the lead post 6 a of the gate lead6 by the wire 15 after the connection of the ribbon strap 53 isfinished.

Next, the semiconductor chip 7, the wire 15 and the ribbon strap 53which constitute connecting means, and portions of the source lead 5 andthe gate lead 6 are covered with a sealing body 2 by sealing them usinginsulating resin.

Next, in the same manner as the embodiment 1, unnecessary portions ofthe lead frame 45 are cut and removed and, at the same time, the leadsare cut by a given length.

According to this embodiment, by using the ribbon strap 53 having alarge width, further lowering of the ON resistance can be obtained. Thepower transistor 1 according to this embodiment 2 also can obtainadvantageous effects substantially equal to the advantageous effectsobtained by the power transistor 1 of the embodiment 1.

Embodiment 3

FIG. 11 is a schematic plan view of a semiconductor device according toanother embodiment (embodiment 3) of the present invention in a statethat a resin sealing body is removed and FIG. 12 is a cross-sectionalview of the semiconductor device.

In this embodiment, the source electrode pad 11 and the source lead 5are connected with each other by the conductive plate 52 in the samemanner as the embodiment 2. However, in this embodiment, as theconductive plate 52, a metal plate 54 molded in a given shape is used.The metal plate 54 is formed of a copper plate, for example. As shown inFIG. 11, the molded metal plate 54 is electrically connected to a sourceelectrode pad 11 and a lead post 5 a of a source lead 5 using anadhesive material 55. As the adhesive material, a conductive resin,solder or the like is used. However, in this case, it is necessary toperform the under barrier metal forming on the surface of the sourceelectrode pad 11. This operation is necessary to prevent an Al surfaceoxide film from impeding conductivity. The under barrier metal layer isconstituted such that, for example, a Ni layer is formed on an Al padsurface and the uppermost portion thereof is formed of Au or Ag whichprevents the oxidation of Ni.

Also in this embodiment 3, lowering of the ON resistance can beobtained. Further, since the metal plate 54 is connected using theadhesive material 55, the operation is facilitated. The power transistor1 according to this embodiment 3 also can obtain the similaradvantageous effect as the power transistor 1 of the embodiment 2.

Embodiment 4

FIG. 13 is a schematic plan view of a semiconductor device according toanother embodiment (embodiment 4) of the present invention in a statethat a resin sealing body is removed.

In this embodiment 4, the source electrode pad 11 in the powertransistor 1 of the embodiment 1 is constituted of two source electrodepads 11 a, 11 b and the respective source electrode pads 11 a, 11 b andthe lead post 5 a of the source lead 5 are connected with each other bywires 14 respectively. This embodiment also adopts the structure thatthe longer the distance g from the center line of the source electrodepad 11 a close to the lead post 5 a, 6 a, the gate electrode pad 12 isarranged at a position farther from the lead post 5 a, 6 a. In FIG. 13,a sealing body 2 is omitted.

Also according to the power transistor 1 of this embodiment 4, in thesame manner as the embodiment 1, the gate electrode pad 12 is arrangedat a position far from the lead post 6 a of the gate lead 6 and hence,the wire bonding is not hampered. Further, the center line portion ofthe source electrode pad 11 a is arranged approximately 2 mm, forexample, from aside of the semiconductor chip 7 close to the lead post 5a of the source lead 5 and, at the same time, the wire 14 is connectedas a first bonding at this portion. Accordingly, it is possible toperform the favorable wire bonding without bringing the bonding toolinto contact with the lead post 5 a. In this manner, provided that thegate electrode pad 12 is arranged at the position which does not hamperthe wire bonding, there arises no problem even when the number of thesource electrode pads 11 is increased to 3 or 4.

In the constitution of this embodiment 4, since a plurality of sourceelectrode pads 11 are provided, the portions where the wires areconnected is increased whereby the wire bonding using the larger numberof wires can be performed and hence, the ON resistance can be lowered.The power transistor 1 according to this embodiment 4 can also obtainthe similar advantageous effect as the power transistor 1 according tothe embodiment 1.

Embodiment 5

FIG. 14 is a schematic plan view of a semiconductor device according toanother embodiment (embodiment 5) of the present invention in a statethat a resin sealing body is removed, FIG. 15 is a cross-sectional viewof the semiconductor device and FIG. 16 is a plan view of a lead frameused in the manufacture of the semiconductor device.

This embodiment 5 is, in the same manner as the embodiment 4, also basedon the technical concept that a plurality of source electrode pads 11are provided and the respective source electrode pads 11 and the sourcelead 5 are electrically connected with each other using connecting meanssuch as wires or the like.

In this embodiment 5, as shown in FIG. 14, the source electrode pads 11are formed in a quadrangular shape having the same size as a gateelectrode pad 12 and are formed in a plural number in a staggeredpattern in the direction which intersects the extending directions(width direction of the support board 3) of the respective leads. Here,to perform the wire bonding effectively, the source lead 5 is arrangedat the center.

FIG. 16 shows a lead frame 45 a which is used in the manufacture of thepower transistor 1 of this embodiment 5. This lead frame 45 a differsfrom the lead frame 45 of the embodiment 1 in the arrangement of theleads. The lead frame 45 a of this embodiment also differs from the leadframe 45 of the embodiment 1 with respect to other points including apoint that the width (length) of the lead post 5 a of the source lead 5is larger than the width (length) of other lead, that is, of the gatelead 6.

That is, in the power transistor 1 of this embodiment 1, as shown inFIG. 14, the source lead 5 is arranged in the center thereof, the gatelead 6 is arranged at one side (left side) of the source lead 5, and thedrain lead 4 is arranged at the other side (right side) of the sourcelead 5. Then, the width of the source lead 5, that is, the width of thelead post 5 a of the source lead 5 is set larger than the width of theother lead (width of the lead post 6 a of the gate lead 6). That is, thewidth (length) of the lead post 5 a is set wide enough to enable theconnection of the lead post 5 a with all of the wires 14 which areconnected to the respective source electrode pads 11 which are arrangedin a staggered pattern. Further, also as shown in FIG. 15, therespective source electrode pads 11 and the lead post 5 a of the sourcelead 5 are connected with each other by the wires 14.

Also in this embodiment 5, the gate electrode pad 12 is arranged at aposition farther than the source electrode pad 11 arranged in astaggered pattern and hence, the bonding tool is not brought intocontact with the lead post 5 a when the wire bonding to the gateelectrode pad 12 is performed. Also with respect to the source electrodepads 11 arranged in a staggered pattern, the source electrode pads 11are arranged far enough from the lead post 5 a of the source lead 5 andhence, at the time of applying the wire bonding to the source electrodepads 11, it is possible to perform the reliable wire bonding whilepreventing the bonding tool from being brought into contact with thelead post 5 a of the source lead 5,

Also in the power transistor 1 of this embodiment 5, the sourceelectrode pad 11 and the source lead 5 can be connected with each otherby a large number of the wire 14, that is, six wires and hence, the ONresistance can be reduced. The power transistor 1 of this embodiment 5also can obtain the similar advantageous effect as the power transistor1 of the embodiment 4.

Embodiment 6

FIG. 17 is a schematic plan view of a semiconductor device according toanother embodiment (embodiment 6) of the present invention in a statethat a resin sealing body is removed and FIG. 18 is a cross-sectionalview of the semiconductor device.

This embodiment 6 is the modification of the embodiment 5. Although thesource electrode pads 11 are arranged in a staggered manner, in theembodiment 5, the source electrode pads 11 are not arranged in astaggered manner. That is, in the same manner as the embodiment 4, thesource electrode pad 11 is formed of two long source electrode pads 11a, 11 b which extend in parallel. Further, out of a plurality of wires14, respective wires are, as shown in FIG. 18, connected to the sourceelectrode pads 11 a, 11 b and the lead post 5 a of the source lead 5.

With respect to the wire bonding according to this embodiment 6, thedistal end of the wire held by the bonding tool is connected to thesource electrode pad 11 a which is arranged far from the lead post 5 aof the semiconductor chip 7 as a first bonding point. Thereafter, thewire is pulled around using the bonding tool and the midst portion ofthe wire is connected to the source electrode pad 11 b of thesemiconductor chip. Then, the wire is connected to the lead post 5 a ofthe source lead 5. Thereafter, the wire is cut at a portion thereof inthe neighborhood of the connecting portion with the lead post 5 a thuscompleting the one-stretch wire bonding. That is, in this embodiment 6,the connection of the wire 14 is performed by stitch bonding. By thisstitch bonding, the source electrode pads 11 a, 11 b and the lead post 5a of the source lead 5 are connected with each other with a plurality ofwires 14. FIG. 17 shows an example which uses 7 pieces of the wires 14.

Also in this embodiment 6, with respect to a plurality of wires 14 whichconnect the source electrode pads 11 a, 11 b and the source lead 5, atthe time of performing the wire bonding of the wire 14 which is arrangedat a side closer to the wire 15 for connecting the gate electrode pad 12and the gate lead 6, there exists a possibility that a short-circuitdefect arises because of contacting of the wire 14 with the wire 15.Accordingly, it is necessary to perform the wire bonding of the gateelectrode pad 12 and the gate lead 6 after the wire bonding of thesource electrode pads 11 a, 11 b and the source lead 5 is finished.

Also in this embodiment 6, the gate electrode pad 12 is arranged at aposition farther than the source electrode pads 11 a, 11 b and hence, atthe time of applying the wire bonding to the gate electrode pad 12, itis possible to prevent the bonding tool from being brought into contactwith the lead post 5 a. Further, with respect to the wire bonding of thesource electrode pads 11 a, 11 b and the source lead 5, the source lead5 is arranged at the center and the lead post 5 a of the source lead 5and the source electrode pads 11 a, 11 b face each other in an opposingmanner while having the same width, favorable wire bonding can beperformed without bringing the wire bonding into contact with the otherlead post or the like. As a result, a large semiconductor chip 7 can befixed to a support board 3.

Also in the power transistor 1 of this embodiment 6, since the sourceelectrode pads 11 and the source lead 5 are connected with each otherusing a large number of wires 14, that is, seven wires, lowering of theON resistance can be realized. The power transistor 1 of this embodiment6 also obtains the similar advantageous effect as the power transistor 1of the embodiment 5.

Embodiment 7

FIG. 19 is a schematic plan view of a semiconductor device according toanother embodiment (embodiment 7) of the present invention in a statethat a resin sealing body is removed and FIG. 20 is a cross-sectionalview of the semiconductor device.

This embodiment 7 is the modification of the embodiment 6. That is, thesource lead 5 which is arranged in the center thereof in the embodiment6 is broadened or enlarged. Although the lead post 5 a of the sourcelead 5 has naturally a large width to allow the connection of aplurality of wires 14 thereto, the lead post 5 a is configured such thatwhole of the lead post 5 a is broadened than the other leads (drain lead4, gate lead 6) to cover even portions of the sealing body 2 which areoutside the lead post 5 a and are projected outwardly from a sealingbody 2. Accordingly, it is possible to radiate heat which is generatedin the semiconductor chip 7 in the inside of the sealing body 2 to theoutside from the broad source lead 5 via a plurality of wires 14 andhence, the stable operation of the power transistor 1 can be realized.The power transistor 1 of this embodiment 7 can also obtain the similaradvantageous effect as the power transistor 1 of the embodiment 6.

Embodiment 8

FIG. 21 is a schematic plan view of a semiconductor device according toanother embodiment (embodiment 8) of the present invention in a statethat a resin sealing body is removed.

This embodiment 8 is also based on the technical concept that, in thesame manner as the embodiment 1, with respect to the lead posts of thecontrol electrode lead (gate lead) and the second electrode lead (sourcelead), the second electrode pad (source electrode pad) is arranged atthe position close to the lead posts and the control electrode pad (gateelectrode pad) is arranged at the position far from the lead posts.

The embodiment 8 also adopts the technical concept that when a pluralityof second electrode pads are further provided, among these secondelectrode pads, the second electrode pad which is arranged close to thelead post is arranged at a position closer to the lead post than thecontrol electrode pad.

A power transistor 1 of this embodiment 8 is the modification of thepower transistor 1 of the embodiment 4. That is, the gate electrode pad12 is arranged in the midst portion of the left side of thesemiconductor chip 7 having a quadrangular shape. Since the gateelectrode pad 12 is provided to the midst portion of the side, thesource electrode pads 11 a, 11 b which are arranged in parallel can beshortened correspondingly.

In other words, one side of the semiconductor chip 7 having aquadrangular shape opposingly faces the lead posts 5 a, 6 a formed ondistal ends of the gate lead 6 and the source lead 5. Then, the gateelectrode pad 12 is arranged at the midst portion of the left side whichis formed contiguously with the opposingly facing side and is arrangedorthogonal to the opposingly facing side. As shown in FIG. 21, the gateelectrode pad 12 is arranged at a position remote by a distance m fromthe center line of the source electrode pad 11 a arranged close to thelead posts 5 a, 6 a. However, in this embodiment, compared to the sourceelectrode pad 11 b which is arranged far from the lead posts 5 a, 6 a,the gate electrode pad 12 is arranged close to the lead posts 5 a, 6 a.Accordingly, the power transistor 1 of this embodiment 8 also can obtainthe similar advantageous effect as the power transistor 1 of theembodiment 1.

Embodiment 9

FIG. 22 is a schematic cross-sectional view of a semiconductor deviceaccording to another embodiment (embodiment 9) of the present invention.This embodiment 9 is the modification of the embodiment 1 and the powertransistor 1 of this embodiment 9 is characterized by the followingstructure. That is, three leads including the drain lead 4, the sourcelead 5 and the gate lead 6 which are projected from an end surface of asealing body 2 are formed such that these three leads are bent in themidst portions and the distal ends of these leads extend from the lowersurface of the support board 3 in a state that the distal ends arepositioned at the substantially same height as the lower surface of thesupport board 3. With respect to extension portions 60 of the distalends of these three leads 4, 5, 6, at the time of fixing the supportboard 3 to the mounting board 3 or the like of the power transistor 1,these extension portions 60 constitute connection portions with linesmounted on the mounting board. The power transistor 1 of the embodiment9 has the surface mounting structure. Here, the drain lead 4 has thesame potential as the support board 3 and hence, it may be possible toadopt the structure in which the drain lead 4 is cut at a proximalportion thereof projected from the sealing body 2 and hence is notconnected to the mounting board. The power transistor 1 of thisembodiment 8 can also obtain the similar advantageous effect as thepower transistor 1 of the embodiment 1.

The invention made by the present inventor has been specificallyexplained based on the embodiments heretofore. However, the presentinvention is not limited to the above-mentioned embodiments and it isneedless to say that various modifications can be made without departingfrom the gist of the present invention. Although, in the embodiments,the explanation has been made with respect to the example in which thepower MOSFET which uses the first electrode, the second electrode andthe control electrode as respective electrodes thereof is incorporatedinto the semiconductor chip, elements to be incorporated in thesemiconductor chip may be a transistor such as power bipolartransistors, an IGBTs or the like or an IC including transistors. Thepresent invention may be applied to at least a semiconductor devicehaving TO-220 structure.

To explain advantageous effects obtained by typical inventions among theinventions disclosed in this specification, they are as follows.

(1) It is possible to provide the semiconductor device having the low ONresistance.

(2) It is also possible to provide the semiconductor device which canfix a semiconductor chip having a larger size to the support board andhence, the high-output semiconductor device can be provided.

What is claimed is:
 1. A semiconductor device, comprising: asemiconductor chip including a field effect transistor and having a mainsurface over which a source electrode pad and a gate electrode pad; asource lead electrically connected to the source electrode pad of thesemiconductor chip via a first conductive material; a gate leadelectrically connected to the gate electrode pad of the semiconductorchip via a second conductive material; and a sealing body sealing thesemiconductor chip, wherein a cross-section area of the first conductivematerial is greater than a cross-section area of the second conductivematerial, wherein, in a plan view from a side of the main surface of thesemiconductor chip, the semiconductor chip has a quadrangular shape, themain surface has a first side, a second side opposite the first side,and a third side extending in a direction which intersects with thefirst and second sides, wherein, in the plan view, each of the sourceand gate leads is disposed more proximate to the first side than theother sides, and wherein, in the plan view, the gate electrode pad isdisposed at a corner portion which is composed of the second and thirdsides.
 2. A semiconductor device, comprising: a semiconductor chipincluding a field effect transistor and having a main surface over whicha source electrode pad and a gate electrode pad; a source leadelectrically connected to the source electrode pad of the semiconductorchip via a first conductive material; a gate lead electrically connectedto the gate electrode pad of the semiconductor chip via a secondconductive material; and a sealing body sealing the semiconductor chip,wherein a cross-section area of the first conductive material is greaterthan a cross-section area of the second conductive material, wherein, ina plan view from a side of the main surface of the semiconductor chip,the semiconductor chip has a quadrangular shape, the main surface has afirst side, a second side opposite the first side, a third sideextending in a direction which intersects with the first and secondsides, and a fourth side opposite the third side, wherein, in the planview, each of the source and gate leads is disposed more proximate tothe first side than the other sides, and wherein, in the plan view, thegate electrode pad is disposed more proximate to a corner portion whichis composed of the second and third sides than a corner portion which iscomposed of the second and fourth sides.